Rotary drilling apparatus.



H E. CARNECHA ROTARY DRELUNG APPA -S.

A'PPLICATIGN FILED JUNE 2&19-18.

1,28%66Z; I Patented Nev. 5, 1918 ROBERT :iLA-RMIQHAEL, mvmme.

W 06 m3 ATTORNEY UNITED STATES- PATENT OFFICE.

ROBERT E. CARMICHAEL, 0F DAMON, TEXAS, ASSIGNOR 0F ONE-HALF T0 GEORGE HAMMAN, OF HOUSTON, TEXAS.

ROTARY DRILLING APPARATUS.

Specification of Letterslatent.

Application filed June 28, 1918. Serial No. 242,452.

To all whom it may concern:

Be it known that 1, ROBERT E. CARMIF.

of which the following is a full, clear, and,

exact description, such "as will enable others skilled in the art to which it appertains to make and use the same.

My invention -relates to rotary drilling apparatus but has particular reference to a device used in connection with core drills in obtaining samples in prospect wells or mines. The core drill is adapted to dig an annular hole leaving in the center thereof a core of the material being'drilled, which core furnishes a sample of the material for the use of the driller. In a process of drilling prospecting wells the cone drill is operated by a rotary. drill stem. This stem is hollow and of a diameter slightly larger than the core left the bit. The pieces of core formed in the drilling operatlon are broken off at stem and are pumped to the surface and discharged for the inspection of the driller. The pump commonly usedin the operation of removing the core from the well is the socalled air-lift pump. The air is introduced under pressure into the drill stem at a point above the bit and bubbles up in the water which fills the inside of the drill stem. The

force of this upward current of air carries with it the water in the stem and creates such an upward suction that it draws into the pipe a constant current of water around the outer periphery of the core being drilled by the bit. In such wells water is almost invariably present in the well but, if such is not the case, water is supplied by being forced down outside the drill stem by means of an ordinary pump. \Vhen pieces of the core break away at intervals the upward current of water carries the broken pieces of core with same and discharges these samples at the surface.

cially thick at the top where the two concentrio pipes find attachment. Due to this fact, it has been impossible to leave-much space outside the drill head and between said head and the walls of the hole. Such a space is necessary, however, to provide sufficient passage for the current of water to -flow"down outside the head to supply the required current to carry out the drill cuttlngs and the broken pieces of the core.

One object of my invention is to reduce the required thickness of the upper end of the drill head in order that suilicient passage for the water may be had.

Another object is to place the connection between the outer air pipe and the drill stem at a point sufiiciently removed above the drill head that no interference will be had with the free operation of the bit.

Other objects and advantages of my improved construction will more clearly appear in the description which follows and Will also be pointed out with more particularity in the claims. lntervals by the whipping about of the drill Referring now to the drawing which forms a part of this specification and in which like numerals are applied to like parts throughout the several views, Figure 1 is a longitudinal section of the drill and the drill stem and is also arranged to show the proper positioning of the air-lift. Fig. 2 is a longitudinal section of my improved drill on the line, 22 of Fig. 3. Fig. 3 is a bottom plan view of my improved core drill. Fig. 4 is a transverse section of my drill on the line 44 of Fig. 2.

My improved core. drill comprises a longitudinal cylindrical head 1, recessed interiorly at the upper end and provided with threads, 2, for attachment to the rotary drill stem 6. The lower end of the head is provided with cutting teeth 3 which have a forward cutting edge 7. This cutting edge is projected inwardly to form a point 5, which acts to cut away the core of material. It will be noted that the core thus obtained will be smaller in diameter than is the central cylindrical recess 8 of the hit. This provides a space outside of the core for the upward passage of the current of water and also revents any wedging or lodging of the core 1n the drill head. The outer surface of the drill head is provided with longitudinal flutes or grooves, 4, of which I have shown four in number. These flutes are of shal- Patented Nov. 5, 1918.

lower depth at the top of the drill head than at the bottom thereof. This arrangement is made in order that the wall of the bit may be of slightly greater thickness toward the top to accommodate the drill stem which must be inserted therein.

It is contemplated that the bit will be attached to the length of drill stem, 6, and at the upper end of this length of stem I provide a compound coupling, 9, threaded interiorly at the base to receive the said stem. At the upper end of said coupling I have provided an inner seat, 10, to receive the lower end of the next length ofdrill stem, I

11, the lower end of which is reduced slightly as shown at Eig. 1,. to fit securely within the seat 10. Spaced slightly outside of this length of pipe, 11, is the outer air pipe, 12, this pipe being threaded within the upper portion of the compound coupling, 9. These two pipes extend upwardly to the surface of the ground, the complete structure being supported and manipulated from the surface by means in common use about drill derricks. Air is forced down from the surface, under compression, in the space 13 provided between the two pipes and finds an inlet into the drill stem at some point above rhe' coupling 9 through openings, let, in the side of the said stem.

By introducing the air at the point above the bit and removed therefrom the same upward suction of the current of water within the drill stem is obtained without the disadvantages resulting from the old form of construction. By this means it is possible to have the flutes, 4, extend the full length of the drill head. thus allowing a free upward passage of the water. This may be done and still leave a suflicient thickness at the upper end of the head to provide a firm and rugged attachment for the drill stem. The coupling 9 is sufficiently removed from the drill so that a large space remains between the coupling and the head for the reception of the required amount of water for the removal of the core and the other disintegrated matter. 7

The point at which the air inlet holes, 14, are placed is determined usually by the depth of the well and the weight of the a head of water standing in the well and it is obvious that the point at which the holes are placed must be changed from time to time. It is necessary that the air be introduced at a point such that the force of the air pressure will not be overcome by the eight of water and other material above the point of inlet and so that the force of the air will be exerted upwardly so as to cause the proper upward current of the water within the well. If the air is intro= duced at a point in the pipe below this point of balance the pressure will sometimes act downwardly and fail to cause the proper upward current. It is proper therefore that the air inlet should be at a point removed somewhat above the bit and in the use of my apparatus this is most easily accomplished.

I have thus provided a bit and apparatus connected therewith which is simple in structure, economical to manufacture and at the same time strong and rugged enough to withstand all the strains to which such a bit is subjected.

Having thus described my improved apparatus what I claim as new and desire to protect by Letters Patent is:

1. Ina rotary core drill, the combination of a head threaded interiorly at the upper end and attached to a drill stem, inwardly curved cutting teeth at the lower end of said drill, longitudinal flutes on the outer periph ery thereof, said flutes being of shallower depth at the upper end to provide greater strength at the point of attachment of said drill to said stem.

2A rotary core drilling apparatus comprising a drill stem, a longitudinally fluted core drill threaded interiorly for attachment to said drill stem, and an air pipe outside said drill stem and joined thereto at a point above said drill, said stem being perforated above said joint.

3. In a rotary core drilling apparatus, the combination of a core drill fluted for its entire length, a drill stem, a compound coupling on said drill stem and spaced above said drill, an outer air pipe spaced outside said stem and secured in said coupling, and means for conducting the air from said air pipe into said stem.

4. In a rotary core drilling apparatus, the combination of a drill fluted exteriorly for its entire length and a discharge means for the core comprising a drill stem, an air pipe spaced outside said drill stem and attached thereto at a point above said bit,-said stem being perforated inside said air pipe for the purpose described.

5. In a rotary drilling apparatus, the combination of a drill fluted exteriorly for its entire length, and a drill stem having an exterior air pipe attached thereto at a point above said bit, and means for the inlet of air from said air pipe to said drill stem.

In testimony whereof, I hereunto affix my signature this the 25th day of June, A. I).

ROBERT E. CARMICHAEL. 

